my car started running rough yesterday, it has occasionally run rough on startup but it usually goes away after a few seconds but this time it hasn't gone away. I pulled plug wires and cylinder 2 has no change with the plug wires removed so I am assuming that cylinder is the problem but when I tried unplugging the injector for cylinder 2 the idle drops and the engine runs rougher. I was trying to determine if the problem was injector or spark because I have 221K on the car, injectors and ignition are all original and I wanted to narrow it down before I start replacing things. I don't have a multimeter so I can't check the resistance on the injectors. What was confusing me is that there is no change in cylinder 2 when the spark is removed but there is a change when the fuel is cut off, does anyone have any ideas?

 

which motor do you have? on a VG you can't individually take fuel away from cyl#2 (cyl2 is near the pass headlight, 6 by the driver headlight, for reference of my lil diagram below)

1 3 5
2 4 6

the injector plug for #2 is covered up by the manifold and you can't unplug it w/o removing the UIM

 

I guess shocks and oil is also original?

If ign REALLY is original, your single cylinder is a true miracle machine. Even one spark a day into right place right time needs lots of bees carryin u electrons. see http://www.cardomain.com/ride/748507/12

Saving the money - instead of investing into 10$ multimeter - will surely increase by itself to the 1500$ u gladly ? pay to the shop - just to receive really abused vehicle (used on track etc), running worse.

Suggestion: Take all that original crap with thick gloves, paint green, throw to the sea for coral growth. Get new, start to maintain u car - no need to ask hlp. Sail happily next 300k.

 

the engine is a vg, I went back and checked and I was unplugging #4 instead of #2. shocks and oil definately aren't original, oil changed every 3k with synthetic and shocks changed 40k ago but the suspension needs an overhaul. I maintain the car well but if it aint broke, don't fix it. that being said, I bought the car used at 131k so they may have been changed before I got it, if they were the guy used oem parts.

 

Ok, I WAS provocative... the mileage seemed incredible. Anyways, even new ign sets can come faulty from shop: cap cracked, new so called wires (=soot hoses) may have resistance over specs (good buy is NGK or best diy REAL wiring). Check also the linky pages 10&14.

 

Why synthetic oil? Its not required and unless you are making alot of horsepower and generating alot of heat its a waste of money. Conventional oil is better for the seals anyway

 

thanks for the tips on the link, I checked the plug wires last year because I was concerned about their age but the resistance was well within spec so I held off replacing them. The distributor does have some buildup and should probably be replaced anyway. My biggest concern is starting to replace parts when I'm not sure what's wrong and end up with a money pit. A friend of mine had a rough engine (ona buick) and replaced all the ignition, injectors, a few sensors and it ended up being a valve problem.

 

If u have original Nissan or some other same inferior class soot tubes, whatever measurement is no good: Any vibration keeps the carbon soot moving, glassfibre is an insulator, not conductor... The rewire is cheap but needs work.

Also check TPS, MAF & O2 signals, relatively easy DIY.

Start from compression tst, gauge is 15$. Do also chassis evaluation: rear wheel wells are ok? Belt, shocks, axles... count the total price, then make a 5yr plan.

 

I have the factory shop manual so I can start going through the sensors once I pick up a multimeter in the next few days. I just moved to indiana from washington state (the desert half) so my car has no rust, I replaced the timing belt two years ago so it has 20k on it, all the other belts appear in good condition. Axels were replaced 4 years ago because of torn boots. The only other major work that needs to be done is an overhaul on suspension, I need to replace the struts, springs, mounts, bushings, boots. I have a set of springs already and I figure the rest of the parts will cost between 500 and 700 if I do my own work.